JPH0443564A - Manufacture of positive plate for sealed lead storage battery - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a positive electrode plate for a sealed lead-acid battery used in a portable device or the like, and particularly relates to an improvement in a drying method after completion of chemical formation.

Conventional technology lead-acid batteries have a high energy density compared to other batteries;
Excellent economy. In particular, sealed lead-acid batteries have recently become VT
Demand for R and small electronic devices is increasing. In terms of characteristics, it has either been significantly improved, or there are still some problems with the remaining capacity and recovery capacity after storage.

Conventionally, after a chemically formed positive electrode plate is removed from the chemical conversion tank after chemical formation is completed, the residual sulfuric acid content on the surface of the electrode plate is washed with water, and the electrode plate is immediately dried.

Problems to be Solved by the Invention However, in the conventional manufacturing method of positive electrode plates for sealed lead-acid batteries,
Since drying begins with a large amount of moisture in the electrode plate, the active material in the electrode plate becomes hot and humid in the early stage of drying, and unstable lead forms at the interface between the lattice and the active material. There was a problem that a lower oxide film was likely to form. The unstable lower oxide film of lead formed at the interface between the lattice and the active material is
When injected, it reacts with sulfuric acid to produce lead sulfate, which is chemically stable and difficult to return to an active state even after charging.If the injected charging state is left for a long period of time, a lead sulfate layer or barrier layer forms, reducing the discharge capacity. There was a problem that it caused variations in the voltage, or that it became impossible to discharge.

The present invention solves these problems and aims to provide a method for manufacturing a positive electrode plate for a sealed lead-acid battery that has excellent storage characteristics.

Means for Solving the Problems In order to solve the above-mentioned problems, the method for manufacturing a positive electrode plate for a sealed lead-acid battery according to the present invention is to heat the positive electrode plate after completion of chemical formation at room temperature for 3 to 30 minutes in a state in which the electrode plates do not come into close contact with each other. The electrode plate was left to stand for ~5 hours to reduce the amount of moisture in the electrode plate, and then dried.

Effect: This prevents the formation of an unstable lower oxide layer of lead at the interface between the lattice and the active material.

EXAMPLE Hereinafter, a method for manufacturing a positive electrode plate for a sealed lead-acid battery according to an example of the present invention will be described with reference to the drawings.

The positive electrode plate was placed in a dilute sulfuric acid chemical conversion solution with a specific gravity of 1.10, and chemical conversion was performed for 20 hours with an electric charge of 0.5 Ah per 1 g of active material.

After completion of chemical formation, two types of drying conditions were compared: (1) drying conditions of the conventional method and (2) drying conditions of the method of the present example. In case (2), after being taken out from the chemical conversion tank, it was washed with water for 1 minute and then dried at 105° C. for 1.5 hours. In case (2), after taking it out from the chemical conversion tank, it was washed with water for 1 minute, and left at room temperature (25° C., 80% RH) for 3 hours without the electrode plates coming into close contact with each other. Thereafter, it was dried at 105° C. for 1.5 hours.

The moisture content in the electrode plate before drying is 0.15cc/1
gAM (AM: active material), ■ is 0.0 because the electrode plates are left in a state where they are not in close contact with each other even though they are at room temperature.
It was 5 cc/IgAM, which was about 1/3 of that of the conventional method.

A battery with a 10 hour rate capacity of 0.2 Ah was constructed using the positive electrode plate produced by the above drying method and compared. The discharge capacity is determined by the capacity of the positive electrode plate. The electrode plate consists of one positive electrode plate and one negative electrode plate, and the amount of positive electrode active material /
The amount of negative electrode active material is 0.8-constant. The specific gravity of the electrolyte was increased from the usual 1.34 to 1 in order to promote capacity deterioration during storage.
．． I increased it to 40. Discharge is 0.8CA, 1.7
5V termination and charging was constant at 2.45V/cell for 8 hours.

Figure 1 shows the change in capacity before and after being left at 40°C. In the case of the conventional example, the variation in the remaining capacity becomes larger as the storage period becomes longer, and the average value is also lower than that of the case of the present example.

FIG. 2 shows the value of the recovery capacity when the remaining capacity was measured and the foot voltage was charged. The battery according to this embodiment shows a recovery rate of 90% or more in the first to second stages of recovery, whereas in the conventional example, some batteries that have been left unused for a long time do not recover at all even after being charged.

Batteries with low capacity measured by the conventional method for residual capacity and recovered capacity were all due to a decrease in the capacity of the positive electrode plate. Further detailed analysis revealed that the lattice surface was covered with an insulating film of lead sulfate, which was the cause of the decrease in capacity. On the other hand, in any case according to this example, an insulating coating layer of lead sulfate as seen in the conventional example was not observed.

Effects of the Invention As is clear from the description of the embodiments above, according to the method for manufacturing a positive electrode plate for a sealed lead-acid battery of the present invention, by leaving it at room temperature after chemical formation and then drying it, no defects are formed at the interface between the lattice and the active material. Since the formation of a stable lower oxide layer of lead can be prevented, a battery with excellent storage characteristics can be provided.

[Brief explanation of the drawing]

Fig. 1 is a graph showing a comparison of the remaining capacity characteristics after being left at 40°C for a battery manufactured by the manufacturing method of a positive electrode plate for a sealed lead-acid battery according to an embodiment of the present invention and a conventional example, and Fig. 2 is a graph showing the same recovery. It is a graph showing a comparison of characteristics.

Claims (1)

[Claims] After taking out the positive electrode plates that have been chemically formed from the chemical conversion tank, the positive electrode plates are left at a temperature of 20°C to 30°C for 3 to 5 hours without being in close contact with each other, and the water content in the positive electrode plates is reduced to 1 g of active material. A method for manufacturing a positive electrode plate for a sealed lead-acid battery, which comprises reducing the amount to a range of 0.03 to 0.05 g and then drying it.